Region's physical development encompasses billions of years

     It developed slowly, this land with its hills, valleys, streams, plants, birds, animals and finally the men who occupy it. Several billion years have been involved in building this area. No one can say exactly how it came about.
     This part of the state has features of geological development that other sections of the state don't have because of its Northern Highland, Central Plan and Western Upland with its driftless area.
     The course of the rivers and sand dunes in the southern parts of the region, stones in the north, varying speed of rivers, location of trees and various soils are, of course, all part of that development.

Can See Evidence

     Rocks in the rivers at certain points are more than a billion years old. There are sand wedges in Eau Claire that confirm that the area was once a tundra similar to land currently inside the Artic Circle.
     Wind has created sand hills on the east side of the Chippewa River from Lake Wissota area downstream. Flambeau Ridge and Barron Hills are part of a mountain building process of about a billion years ago.
     In most recent epochs, directional changes of the Chippewa River and the Buffalo River, for instance, are post glacier events and have happened within the past 10,000 years.
     The area has been mountainous, covered by oceans and glaciers, in parts, at least four different times. Long periods of erosion have been responsible for rich soils, sandy loam, valleys and hills today.
     It didn't become this way overnight.
     Sometime, maybe 3.5 billion years ago, pressure within the earth exploded and heat forced mantle material from within. This process continued many times as the earth heated, cooled and again rebuilt new shapes which were eroded and redesigned by the work of wind and water.
     The area has been mountainous, covered by oceans and glaciers, in parts, at least four different times. Long periods of erosion have been responsible for rich soils, sandy loam, valleys and hills today.

Formed three billion years ago

Rocks in the Chippewa River near Jim Falls represent basement rock laid down when the area was first formed by active volcanoes. Rocks formed by lava have been smoothed by water for thousands of years. Cutting by the river has exposed these. Most of the area has sandstone layers above these rocks.

     Some three billion years ago, during one of these upheavals, in what is called the Precambrian era during the Archean period, a formation of the complex igneous and metamorphic rocks of Northern Wisconsin took place following many periods of erosion, sedimentation and volcanism.
     Examples of these rocks can be seen today, for instance, in the Chippewa River at Jim Falls. They were formed as magma from the erupting earth spread with the purer parts solidifying with the crust and then cooled slowly, creating a deep hard rock.
     Years of water running over layers of material above exposed these bedrocks from the Precambrian era.
     These rocks deep within the earth provided what is generally termed the "fall line." Many early cities along the Appalachian mountains were developed there because of the speed of the water as it crossed rapids created by the exposed rock.

Created Ideal Sites

     Places such as Black River Falls, River Falls, Chippewa Falls were ideal sites for early saw and grist mills because of the same principle proving for water power.
     More mountain building took place about 2.4 billion years ago in the norther regions when the Flambeau Ridge and Barron Hills were developed during the Animikian Period.
     About 1.5 billion years ago the other mountains in the area had eroded and because of the more solid basement material in the core of these monadnocks, erosion had taken much longer.
     Also, the Ice Age, as will be developed later, did not have as great an effect on these hills and ridges.
     At this time the earth underwent another change in this area, called the Keweenawan Period, when the Lake Superior syncline and the deposition and building of sandstone took place.
     This ridge of mountains ran from Eastern Minnesota across Northern Wisconsin and into Canada. They are called the Keweenawan-Laurentain mountains by geologists.
     Examples of these rocks are various kinds of granite, rhyolite, basalt and grantic gneiss. Wind and rain for nearly a billion years wore much of this area down, and ended what is known as the Precambrian era of older, predominately crystalline rocks.
     The St. Croix River has been cut to a depth of 200 feet into lava flows from the Keweenawan period.
     The earth then went into a cooling period which lasted until 500 million years ago, during what is called the Paleozoic Era.

State is submerged

     During this period, Wisconsin was submerged, possibly four times, by great seas and oceans. Great sediments started to form at the bottom of the oceans burying Precambrian landscape and other basement complexes beneath as much as several thousand feed to sedimentary rocks.
     Sandstones in this area are evidence of the periods when great seas covered the area. Sands eroded from nearby mountains, probably from the northern Keweenawan mountains, and build up on the bottoms of the sea.
     Within these sandstones have been parts of shells from trilobites, three lobed creatures. These fossils are believed to be from 200 million to 600 million years old.

Examples visible here

This outcropping of Mt. Simon Sandstone is familiar to persons living in Eau Claire as it represents one of the highest points in the city. Because of the nature of the material, the weathering process has been resisted. It was laid down in these layers by oceans which once covered this part of the state.

Mt. Simon Sandstone, presumably the oldest Cambrian formation in Wisconsin, rests uncomfortably on weathered pre-Cambrian granite. This geological feature is located in Irvine Park in Chippewa Falls on the east side of Duncan Creek.

     Examples of sandstones have been noted here and can be seen at Mt. Simon in Eau Claire. It has been termed Mt. Simon sandstone because of the location where it comes out of the ground. The same type of sandstone has again surfaced in the western part of Tennessee.
     Mt. Simon sandstone sits atop a granite basement stock from billions of years ago.
     This sandstone is also visible on the east side of Duncan Creek in Irvine Park in Chippewa Falls. The Mt. Simon formation has been described in a geological survey of this area as clean, white, unfossiliferous sandstone about 250 feet thick.
     On top of it is what has been termed Eau Claire sandstone. An example of this is located at a road cut south of Eau Claire near the junction of U.S. 53 and CTH II. Local examples can be found near Mt. Washington.
     There are other evidences of Eau Claire sandstone in the area. Between Independence and Arcadia are several cuts exposing the stone.

Correlated with fossils

     Eau Claire sandstone has been correlated with fossils with sands of the same age in Texas, Pennsylvania, New York and in several European countries.
     The same process which developed these two types of sandstone was believed to have continued into other periods during which Wisconsin was submerged.
     During the late Paleozoic Era, perhaps 250 million years ago, a period of gentle uplift began which has continued to the present. During this time, land surface was again carved by rain, wind and running water.
     The ridge of hills west of Arcadia toward Fountain City is an example of the work of water and wind as the harder materials in the ridge have been eroded to a lesser degree than side materials.
     For the next 1.5 million years there was continued erosion of Wisconsin and progressive removal of Paleozoic sedimentary rocks. Included in this period was the formation of deep valleys of the driftless area and exposure of the formerly buried Precambrian rocks and associated monadnocks in Northern Wisconsin.
     These periods of development covered the Mesozoic and Cenozoic Eras.
     Glaciation in Wisconsin is relatively recent in the march of time when writing about development of the area. During the Pleistocene Epoch or "Ice Age" which began about one million years ago, there were four separate glacial advances, each followed by an interglacial period when the ice receded.

Evidence of tundra remain

     Evidence of early glacial periods still remain in Eau Claire. Periodically, it has been noted, certain sand wedges are found in soil for no apparent reason. These wedges are usually about three feet across and about six feet deep.
     These findings date back thousands of years to when the area was a tundra similar to the Artic Circle. During this period there was permafrost in the ground. That occurs when the ground is frozen so hard that even during the warm months, not all the frost is drawn out.
     In these wedge-shaped areas were frost and water. When the climate between the glacial periods warmed, the ice and grost melted, leaving holes in the ground. Over the years wind carried sand and other lightweight particles across the land and deposited them in these holes.
     The glaciers were so named because of the material deposited at the end of them. Names included in their order the Nebraska, Kansan, Illinoian and the Wisconsin. It was the latter which had the most current influence on this area.

Long accumulation of snow

     They were formed by the continuous accumulation of snow. Snow then turned to ice which reached a maximum thickness of almost two miles. The front of the advancing ice sheet had many tongues or lobes whose direction and rate of movement were controlled by topography of the land surface over which they formed.
     Glaciers carried a great amount of rock debris called drift. Some of this was deposited under the ice to form ground moraine and was piled up at the margins of the ice lobes to form end or terminal moraines.
     It was the Chippewa lobe that moved into the area and covered a great portion of the upper Chippewa Valley, reaching as far south as Bloomer, between Jim Falls and Chippewa Falls and better than one-half of Taylor County.
     When the glacier halted, it left much of the center of Barron County unaffected, but covered all but a few miles of Polk County to the west.
     Although counties to the south were not covered, it did eventually affect geology of this region because of the vast amount of water it released and sediment it carried with it.

Buffalo River changes course

     Some believe the Buffalo River once flowed into the Chippewa and on to the Mississippi. However, because of the great flow of water and ice coming down the Chippewa, the Buffalo River was backed up and eventually cut its own channel south toward the Mississippi.
     Action of the ice profoundly modified the landscape, smoothing off the crest of hills and filling valleys with drift. In some place it changed the course of the rivers, forcing them to cut new channels.
     The highway between Alma and Fountain City, for example, is built for the most part on sand and gravel terrace. Well borings, one of the best ways to determine composition of the upper part of the earth, indicates a 75 to 80 foot thickness at Fountain City and a depth of 100 feet of sand and gravel at Alma.
     Another example of change is that some feel the Chippewa River did not originally go through the Holcombe-Cornell area, but rather came south somewhere neat Eagle Point in Chippewa County.
     Some deep wells drilled in that area give evidence of a break in the bedrock where the river may have flowed. However, there have not been enough wells or evidence to substantiate this.
     It was probably the Flambeau River which came down through Jim Falls.

Ice Age Trail follows area

     Ice Age Reserve and Ice Age hiking trails pass through much of the terminal moraine created 10,000 years ago.
     Along this trail other features of the ice age are pointed out -- including kames, perfectly cone-like in shape, caused by holes in glaciers through which water carrying debris swirled, leaving an hourglass-bottom deposit on the land's uneven surfaces. Also eskers or ridges of glacial deposit which contain gravel and stones with well-rounded edges from tumbling along streams under the glaciers, and ice-blocked lakes and potholes numerous in the areas where the glacier ended.
     West of Rice Lake are a number of lakes. This area was covered by ice sheets. When the ice melted, left behind were a number of steep-banked lakes.
     The sand and gravel which accumulated alongside the sheets of ice remained to form lakes when the last of the ice melted.
     Unglaciated parts of our area where also affected by glaciers to the north, particularly some of the fertile farm lands. Much of the finer mineral material from the end of the glaciers washed down streams.
     Thus, outwashed plains were created, adding to the richness of the soil. Just north of Chippewa Falls on Hwy. 124 is a good example of a fertile outwash plain.
     Still another is near Rice Lake where an outwash plain, developed by the streams from the ice sheet. Well drillings show that beneath the gravel deposits is sandstone.
     Before the last glacier era, the area from near Luck southwest to Merrillan resembled the area around Camp Phillips today.
     Other materials such as sand and gravel were washed down streams and deposited along the banks.

River beds became altered

     Melting of glaciers forced more water into streams. Thus much of the Chippewa River bed from Chippewa Falls to Durand has been altered, some of it dating from the Pleistocene glacier period.
     The Chippewa River course within the city of Eau Claire has changed several times since the Wisconsin glacier receded.
     Evidence of the change is Half Moon Lake, mow a meander scar or an ox bow lake.
     The Chippewa at one time came through on the opposite side of Mt. Simon, cut back through where Little Niagara Creek is located in Putnam Park, went west, cut through Half Moon Lake and then almost straight south.
     Among the first changes was the backing up in current Dells Pond and the cutting through hard sandstone at Dells Dam. Because of its speed, the river cut off the Putnam Drive area and swung straight west.
     With its new gradient, velocity of the water chewed out a new channel and bypassed the swing through Half Moon Lake, digging a new channel.

Sand base slowed flow

     As the river went into the sandier soils of the Eau Claire area it cut deeper and had less resistence, thus with less speed and a lower gradient, it was easier for it to meander and form new channels.
     Other geological evidence in Eau Claire is the presence of sand dunes on the east side of the river, for example along City View Drive.
     These were created because of the work of wind on uncovered sandstone along the east bank of the river. Wind over the years loosened the surface and then dumped sand. Some of it is carried as far away as the present London Square Mall site.
     The same principle was at work on the west side of Lake Hallie and along the river in the Lake Wissota area.

River valley changes continue

     In Eau Claire, again, for instance, all of the area above the valley is much like it was before the Wisconsin glacier. However, the river valley itself has been changed considerably since the last glacier.
     It is difficult because of the vast amount of time to project the direction in which the geology of the area is moving. Worldwide it could be moving back to another ice age or, on the other hand, it may become warmer, melting the polar ice caps and drowning cities on the coasts.
     Whatever happens, any change in geology of the region will take thousands of years if it follows past patterns.

--Arnie Hoffman

Extracted from the Eau Claire Leader Telegram
Special Publication, Our Story 'The Chippewa Valley and Beyond', published 1976
Used with permission.